The control of lipid biosynthesis is an important and unsolved problem in cell biochemistry. Since lipid synthesis, and consequently membrane synthesis, is necessary for growth, it is necessary that the mechanisms which control the composition and quantity of the membrane lipids be understood. The proposed research is designed to study the regulation of lipid biosyntheis in bacteria as a model system. An approach to this objective will involve characterizing several types of E> coli mutants which, despite the fact that they harbor a defective lipid biosynthetic enzyme, can synthesize lipids at a normal rate. These mutants may owe their phenotype to defects in regulatory genes. Genetic, physiological, and biochemical studies will be performed on these mutants in an attempt to understand the molecular basis for maintenance of normal lipid synthesis. In another study, attempts will be made to purify and characterize an induced protein factor required for the initiation of free fatty acid production in the absence of phospholipid synthesis. It is hoped that the information obtained from these studies will aid in understanding the mechanism(s) by which fatty acid synthesis is regulated.